This invention relates to extensometers.
Extensometers wherein a change in electrical capacitance due to displacement of a member is related to extension are known. Typically, in such an instrument the capacitance surfaces comprise relatively displaceable plates and in a hostile environment there can be difficulty in providing flexible electrical connections which can accommodate the movement. Extensometers which make the use of variable electrical capacitance are hereinafter referred to as extensometers of the capacitance kind and an object of the invention is to provide an extensometer of the capacitance kind which is sufficiently robust to be capable of operation for long periods without maintenance in a high temperature and hostile environment.